For floor panels and wall panels, the visual appearance is very important. Furthermore, due to new regulations it is important to introduce properties that can reduce the level of indoor volatile organic compounds (VOC's).
It is well known that building materials can obtain photocatalytic properties. U.S. Pat. No. 6,409,821 describes how to apply TiO2 to external cement building materials by mixing micron sized TiO2 in the bulk cement mixture.
Furthermore, it was shown in WO 2009/062516 that it is possible to apply nanoparticles on a laminate surface or on an overlay paper and introduce photocatalytic properties to interior surfaces such as floor panels.
US 2010/0058954 describes a carbon-modified titanium dioxide film arranged on a substrate such as glass, metal, plastic or titanium dioxide film. A barrier layer may be arranged to prevent potential diffusion of sodium and other ions from the substrate into the carbon-modified titanium dioxide film. The photocatalytic activity can be inhibited by diffusion of sodium and other ions from the substrate.
PCT/SE2012/050703 (not yet published) describes a photocatalytic layer and a barrier layer.
It has also been discovered that the photocatalytic activity of the nanoparticles degrade not only volatile organic compounds but also underlying surfaces to which the nanoparticles are applied.